Treatment of raw sewage in any locality is and remains a problem. It is well known that raw sewage can spread typhoid fever, dysentery and cholera. It also can contaminate large bodies of water into which the untreated sewage is discharged. Further, as raw sewage decomposition occurs in a large body of water, it depletes the oxygen normally present in the water which can result in the destruction of all marine life due to the depletion of the life sustaining oxygen.
Thus, the treatment of raw sewage is typically designed to remove or alter the objectionable suspended and semi-solid or solid materials in the raw sewage so that the resulting liquor may be safely disposed in a large body of water or leached into the soil without the destructive side effects.
Typical commercial raw sewage treatment systems are known as "water carriage systems" which include sewer mains (pipes) which carry the raw sewage to a common site for treatment. The semi-solid or solid materials in the raw sewage in these systems represents approximately 0.2% by volume with 99.8% of the effluents composed of water. Obviously in such conventional sewage systems, the high water content poses a significant problems in treatment due to its large volume, especially when a considerable amount of volunteer water enters the sewage piping or carry system. Many building codes restrict the connection of downspouts and the like to commerical sewage carry systems due to the difficulty in treating the large volume of raw sewage resulting when augmented by rain water from storm drains and the like.
In rural areas where water carriage sewage systems are unavailable, raw sewage disposal has been typically handled either by cesspools or septic tanks. Prolonged use of cesspools can often result in the saturation of the surrounding soil, which in time can cause very unsanitary conditions. Further, soil formations which are stratified often have cracks through which polluted effluent from said cesspools may travel great distances without dilution or natural filtration, thereby causing contamination of ground water and/or wells furnishing drinking water.
Currently dwellings in rural areas, by building codes, are required to have septic tanks which are presumably watertight and which permit the settling of sewage solids in a large chamber so bacterial decomposition of these settled solids can take place at the bottom of the tank. An outlet pipe adjacent to top of the tank and the surface of the fluid level in the septic tank allows the liquid to be decanted from the sediment in the septic tank and distributed into a leach field or alternatively discharged into streams and lakes.
The discharge of the treated liquid into leach fields or streams and lakes can be environmentally sound only if the septic tank system is functioning properly. However, often times in septic tanks the solids do not completely settle and may actually leave the septic system with the decanted liquor. This often causes plugging of drain fields where the liquor is pumped for leaching along with the pollution of leach field and/or streams or lakes in which the liquor is discharged.
As can be appreciated by the foregoing discussion, one of the difficulties in treating raw sewage is due to the significant amount of water in the sewage effluent. Applicant has found that if the feculent semi-solids are solids are removed immediately from the raw untreated influent and allowed to undergo aerobic bacterial digestion, the effectiveness of the subsequent digestion in a septic tank is improved to the degree that the liquor leaving the septic tank is pollution free and devoid of all suspended organic solids.
Due to the organic-free character of the liquor leaving the septic tank in the current invention neither pumps nor leach fields will be plugged when the decanted liquor passes through them. In addition the clear liquor is environmentally safe and of sufficient purity that even if percolation is inadequate to prevent the liquor from surfacing in the drain or leach field, no health hazard will occur.
Applicant is aware of a number of patents which relate to treating feculent wastes. These patents include U.S. Pat. No. 408,506 issued to McClellan, U.S. Pat. No. 1,539,255 issued to George, and U.S. Pat. No. 3,546,718 issued to Minnitte which is probably the most relevant of this group of patents. Also, applicant is aware of several British patents dealing with treatment of wastes, including British Pat. Nos. 22,276 and 25,844.
In reference to the invention, applicant has developed a sewage treatment system which is trouble free and does not require the normal maintenance commonly experienced with septic tank operation in rural areas.
Still another advantage of applicant's invention is that the liquor leaving the septic tank portion, being free of all organic matter, will leach at much lower percolation values than possible when using conventional septic tanks.
Also another advantage is that the decanted liquor leaving the septic tank portion of the current system is biologically inactive, pollution free and environmentally safe.